钢管混凝土空间KK相贯节点力学性能研究.pdf 13页

'中国科技论文在线http://www.paper.edu.cnFiniteelementmodellingandnumericalinvestigationof#multi-planarconcrete-filledsteeltubularKKjoints1,21*5CHENJuan,ZHOUChengye(1.DepartmentofCivilEngineering,NanjingUniversityofAeronauticsandAstronautics,210016;2.DepartmentofCivilEngineering,TsinghuaUniversity,100084)Abstract:Withthedevelopmentoflargespanandheavyloadmodernengineering,concrete-filledsteeltubularstructuresappearconstantly.Thejointsofthesestructuresaremostlymulti-planarjoints.10Inordertosolvetheproblemoflackingoftheinvestigationofmulti-planarconcrete-filledsteeltubular(CFST)joints,themechanicalbehaviourofCFSTKKjointswerestudiedthroughrefinedfiniteelementsimulation.AccuratefiniteelementmodelsofCFSTKKjointswereestablishedbyconsideringthematerialnonlinearity,thegeometrynonlinearity,andthecontactnonlinearitybetweenthetubeandtheconcrete.Thespatialeffectofmulti-planarjointswasbeobtainedbycomparingwith15uni-planarjoints.TheFEMresultsshowedthat,themulti-planarcarry-overeffectshadthemaximumeffectforthe60oCFSTjoints,thestrengthofmulti-planarjointsdecreasedcomparedwiththeplanarjoints,andthestiffnessofthemdidnotvarysubstantially.Whileforthe90oCFSTjoints,boththestrengthandstiffnessofmulti-planarjointsdidnotvarysubstantiallywiththeplanarjoints.Thisresearchcanprovidescientificbasisforthedesignofmulti-planarCFSTjoints,andeffectively20promotetheapplicationofCFSTstructures.Keywords:steel-concretecompositestructure,tubularjoint,multi-planarjoints,failuremode,refinedfiniteelementsimulation0Introduction25Concrete-filledsteeltubular(CFST)structureisatypeoftubularstructurewhichusesconcrete-filledsteeltubeasitschordandhollowsteeltubeasitsbrace.Fillingconcreteintothesteeltubeisaneffectivewaytoincreasethestaticcapacityofjoints[1-3]andreducethestressconcentrationfactorsandthustoenhancethefatiguelife[4-9].Duetothebenefitofexcellentstructuralperformanceandconstructionaladvantages,multi-planarjointsarefrequentlyusedin30CFSTstructuresinChina[10,11],e.g.inlargespanbridges,offshorejacketstructures,pipelinestructures,triangularorquadrangulargirders,asshowninFigure1.a)GanhaiziBridgeb)WushanYangtzeRiverBridge35图1钢管混凝土空间相贯节点在中国的应用Fig.1Applicationofmulti-planarCFSTjointsinChinaResearchoncircularhollowsection(CHS)steeltubularjointsshowsthatmulti-planareffectareindeedsignificantforsomekindsofCHSjoints[12-17].Inthepastdecades,extensiveFoundations:NationalNaturalScienceFoundationofChina(No.51408308),SpecializedResearchFundfortheDoctoralProgramofHigherEducation(20133218120009),OpenResearchFundProgramofStatekeyLaboratoryofHydroscienceandEngineering(No.sklhse-2016-C-04),NUAAFundamentalResearchFund(No.NS2014001).Briefauthorintroduction:JuanChen(1982.10),Female,Lecture,Steel-concretecompositestructure.E-mail:chenjuan@nuaa.edu.cn-1- 中国科技论文在线http://www.paper.edu.cn40researchstudieshavebeenconcentratedonthemechanismbehaviorofuni-planarCFSTjoints[18-21]andCFSTtrusses[22-25],andthereisstilllackofresearchonmulti-planarCFSTjoints.ResearchalsoshowsthefailuremodesandtheresistantofCFSTjointsaresignificantdifferentfromCHSjoints.Soresearchonthemechanicalperformanceofthemulti-planarCFSTjointsbecomesanimportantsubject.451Finiteelementmodeling(FEM)ThefiniteelementprogramANSYS[26]wasusedinthesimulation.InordertoaccuratelysimulatetheactualbehaviorofCFSTjoints,themaincomponents,includingtheconfinedconcrete,thecircularhollowsteeltube,andtheinterfacebetweentheconcreteandthesteeltubehadtobemodeledproperly.Inaddition,carefulattentionwasgiventothechoiceoftheelement50typeandmeshsizetoachievingahighlevelofnumericalaccuracyandstabilitywithoptimumcomputationalefficiency.1.1FiniteelementtypeandmeshDifferentelementtypeshadbeentriedandsolidelementswerefoundtobemoreefficientinmodelingthesteeltubeandtheconcreteaswellasthecleardefinedboundariesoftheirelements.55Three-dimensionalcontinuumbrickfiniteelementSOLID45wasusedtomodelthesteeltubeandtheweld.TheSOLID45elementwasusedforthe3-Dmodelingofsolidstructures.AreducedintegrationoptionwithhourglasscontrolisavailablefortheSOLID45element.Theconcreteinsidethesteeltubewasmodeledusingeight-nodebrickelementSOLID65.TheSOLID65elementissimilartotheSOLID45elementwiththeadditionofspecialcrackingandcrushing60capabilities[27].ThecontactbetweenthesteeltubeandtheinsideconcretewasmodeledbyCONTA174andTARGE170element.TARGE170wasusedtomodeltheinnersurfaceofthesteeltubeandCONTA174wasusedtomodeltheoutersurfaceoftheconcrete.Thefrictionbetweenthetwofaceswasmaintainedaslongasthesurfacesremainincontact.Thecoefficientoffrictionbetween65thetwofaceswastakenas0.6intheanalysisasrecommendedbyHanetal.[28].Theinterfaceelementallowedthesurfacestoseparateundertheinfluenceofatensileforce.However,thetwocontactelementswerenotallowedtopenetrateeachother.Ameshconvergencestudywasperformedsoastoidentifyanappropriatemeshdensitytoachievereliableresultswithreasonablecomputationtimes,thecorrespondingaveragegridsizefor70themeshofchordtubes,bracetubesandconcretewas30,20and40mm,withrelativelydensemeshingatcriticalareas.Figure2showsthefiniteelementmodelofaCFSTKjoint.ConcreteofthechordSteeltubeofthechordSteeltubeofthebracea)Testspecimenb)FEMofspecimenc)targetelementd)contactelement75图2钢管混凝土Ｋ型相贯节点的有限元模型Fig.2FEMofCFSTKJoint-2- 中国科技论文在线http://www.paper.edu.cn1.2BoundaryconditionsandloadapplicationFollowingthetestingprocedurepresentedbyWenjinHuangetal.[29],thebottomsurfaceofthechordwasfixedagainstalldegreesoffreedom,andthetopsurfaceofthechordwasfixed80againsttwodegreesoffreedom.Theloadwasappliedatnodesofthebraceend.1.3MaterialmodelingInthefiniteelementmodel,thestrengththesteelofchordandbracemembersoftheCFSTKjointspresentedbyWenjinHuangetal.[29]wasused.ThematerialbehaviorprovidedbyANSYSallowsamulti-linearstress-straincurvetobeused.Thefirstpartofthemulti-linearcurve85representstheelasticpartuptotheproportionallimitstresswithmeasuredYoung’smodulus(200,000MPaforsteeltubes)andPoisson’sratioequalto0.28.IntheCFSTjoint,theconcreteisintri-axialcompressionstatue,thereforeconfinedconcretemodelproposedbyHanetal.[30]wasusedinthisstudy.2Verificationoffiniteelementmodel90TheexperimentalinvestigationsonCHSandCFSTKjointspresentedpreviously[28]wereusedtovalidatetheaccuracyoftheFEMinsimulatingCFSTKjointsinthisstudy.Thethicknessandthediameterofthechordandthediameterofthebraceallthespecimensareallthesame.Thetestspecimensarelabeledsuchthatthechordtype,where“S”referstosteeltubeand“CS”referstoconcrete-filledsteeltube,thicknessofbrace,thetypeofthejoints,andanglebetweenthebraces95onlyformulti-planarjoints.ThefailuremodesandthestrengthofspecimensobtainedfromtheFEMwerecomparedwiththetestresults,asshowninFigure3andTable1.ThecomparisonindicatesthattheFEMisabletopredictthefailuremodesandthestrengthoftheCHSandCFSTspecimensclosely.100图3试件破坏模式和有限元模拟结果的对比Fig.3Comparisonoftheobservedandpredictedfailuremodeofspecimens-3- 中国科技论文在线http://www.paper.edu.cn表１试验和有限元承载能力对比Tab.1StrengthvaluesobtainedfromtestandFEMFailuremodebytestingJointstrengthbyJointstrengthbyRatiobetweentestSpecimenandFEMtestingFEMandFEMjoint(kN)(kN)(kN)strengthS-6-KChordfacefailure71765091%S-8-KChordfacefailure71966492%BracefailureandCS-6-K11151284115%PunchingshearfailureCS-8-KPunchingshearfailure15411575102%CS-10-KPunchingshearfailure1612157698%1053AnalysisanddiscussionsTheverificationshowedthattheFEMofCFSTKjointswasreasonablyaccurate.Hence,furtheranalysiswascarriedouttostudythemechanicalpropertiesoftheCFSTKKjoints.InordertofindthediffrencebetweentheCFSTKjointsandtheCFSTKKjoints,theuni-planarKjointswhichhadanidenticalconfigurationandloadingofthebraceswereanalysedforcomparing,and110theCHSjointswhichhadanidenticalconfigurationandloadingofthebraceswereanalysedforcomparingtoo.Bothmaterialandgeometricnon-linearitywereconsideredintheanalysis.3.1ComparativeanalysisofCHSjointsTheFEMresultsshowedthatthechordfacefailuremodeoccurredinbothCHSKjointandKKjoints,asshowninFigure4,Figure6andFigure8.ThemaximumstrainofalltheCHSjoints115occursatthechordareaofcompressionbrace.ThechordsofalltheCHSjointsyielded,whilethebracesdidnotyield.Thestressandstrainnephogramsofthemuti-planarjointsandplanarjointswereclose.ComparingtheKKjointswithdifferentbraceangle,wecouldfoundthegreatertheangleofthebrace,thegreatertheyieldofthechord.TheaxialloadversusaxialdeformationdiagramsofthebracesofCHSKandKKjointsareshowninFigure5,Figure7andFigure9.Foro120the60joints,S-6-KK-60,S-8-KK-60,andS-10-KK-60,themulti-planarjointsstrengthandtheostiffnessincreasedslightlycomparingwiththeplanarjoints.Forthe90joints,S-6-KK-90,S-8-KK-90,andS-10-KK-90,themulti-planarjointsstrengthdecreasedsubstantiallycomparingwiththeplanarjoints,whilethestiffnessofthemwerealmostthesame.125-4- 中国科技论文在线http://www.paper.edu.cna)StainnephogramsofS-6-Kb)StressnephogramsofS-6-K130c)StainnephogramsofS-6-KK-60d)StressnephogramsofS-6-KK-60e)StainnephogramsofS-6-KK-90f)StressnephogramsofS-6-KK-90图4S-6系列应变和应力云图135Fig.4StainandstressnephogramsofS-6series图5S-6系列支管荷载-位移曲线Fig.5ComparisonbetweentheaxialloadversusaxialdeformationdiagramsofthebracesofS-6series140-5- 中国科技论文在线http://www.paper.edu.cna)StainnephogramsofS-8-Kb)StressnephogramsofS-8-Kc)StainnephogramsofS-8-KK-60d)StressnephogramsofS-8-KK-60145e)StainnephogramsofS-8-KK-90f)StressnephogramsofS-8-KK-90图6S-8系列应变和应力云图Fig.6StainandstressnephogramsofS-8series150图7S-8系列支管荷载-位移曲线Fig.7ComparisonbetweentheaxialloadversusaxialdeformationdiagramsofthebracesofS-8series-6- 中国科技论文在线http://www.paper.edu.cna)StainnephogramsofS-10-Kb)StressnephogramsofS-10-K155c)StainnephogramsofS-10-KK-60d)StressnephogramsofS-10-KK-60e)StainnephogramsofS-10-KK-90f)StressnephogramsofS-10-KK-90图8S-10系列应变和应力云图160Fig.8StainandstressnephogramsofS-10series图9S-10系列支管荷载-位移曲线Fig.9ComparisonbetweentheaxialloadversusaxialdeformationdiagramsofthebracesofS-10series-7- 中国科技论文在线http://www.paper.edu.cn3.2ComparativeanalysisofCFSTjoints165InFEMoftheCFSTjoints,thefailuremodesoftheKandKKjointswiththesamegeometrywerethesame,andtwotypesoffailuremodeswereobserved.BraceyiledfailuremodeoccurredinthecompressionbraceofthespecimenCS-6(t=6mm),asshowninFigure10,whilethespecimensCS-8andCS-10(t=8and10mm,respectively)failedforchordpunchingshear,asshowninFigure12andFigure14.Moreover,thespecimensCS-8andCS-10inwhichthechord170punchingshearfailuremodesoccurredhadmuchlargerstrengthandultimatedeformation.ComparingwiththeCHSjoints,thestrengthofCFSTjointsweremuchhigher,andthefailuremodesofthemweredifferent,whichshowsthatadoptingaconcrete-filledchordmemberistheomosteffectivewaytoimprovethestrengthofCHSjoints.Forthe60joints,CS-6-KK-60,CS-8-KK-60,andCS-10-KK-60,themulti-planarcarry-overeffectshadthemaximumeffect,the175strengthdecreasedcomparedwiththeplanarjoints,whilethestiffnessofthemdidnotvaryosubstantially.Forthe90joints,CS-6-KK-90,CS-8-KK-90,andCS-10-KK-90,boththestrengthandstiffnessdidnotvarysubstantiallywiththeplanarjoints.Thiswasbecausetheanglestheooobraceofthe90jointswerelargerthanthe60joints,thebracesofthe90jointscouldbeapproximatedseemedastwopairsofindependentplanarbrace.180a)StainnephogramsofCS-6-Kb)StressnephogramsofCS-6-Kc)StainnephogramsofCS-6-KK-60d)StressnephogramsofCS-6-KK-60185e)StainnephogramsofCS-6-KK-90f)StressnephogramsofCS-6-KK-90图10CS-6系列应变和应力云图Fig.10StainandstressnephogramsofCS-6series-8- 中国科技论文在线http://www.paper.edu.cn图11CS-6系列支管荷载-位移曲线190Fig.11ComparisonbetweentheaxialloadversusaxialdeformationdiagramsofthebracesofCS-6seriesa)StainnephogramsofCS-8-Kb)StressnephogramsofCS-8-Kc)StainnephogramsofCS-8-KK-60d)StressnephogramsofCS-8-KK-60195e)StainnephogramsofCS-8-KK-90f)StressnephogramsofCS-8-KK-90图12CS-8系列应变和应力云图Fig.12StainandstressnephogramsofCS-8series-9- 中国科技论文在线http://www.paper.edu.cn200图13CS-8系列支管荷载-位移曲线Fig.13ComparisonbetweentheaxialloadversusaxialdeformationdiagramsofthebracesofCS-8seriesa)StainnephogramsofCS-10-Kb)StressnephogramsofCS-10-K205c)StainnephogramsofCS-10-KK-60d)StressnephogramsofCS-10-KK-60e)StainnephogramsofCS-10-KK-90f)StressnephogramsofCS-10-KK-90图14CS-10系列应变和应力云图Fig.14StainandstressnephogramsofCS-10series-10- 中国科技论文在线http://www.paper.edu.cn210图15CS-10系列支管荷载-位移曲线Fig.15ComparisonbetweentheaxialloadversusaxialdeformationdiagramsofthebracesofCS-10series4SUMMARYANDACKNOWLEDGMENT215Thefollowingconclusionscanbedrawnbasedontheresearchworkreportedinthispaper.(1)Afiniteelement(FE)modellingwasdevelopedtostudythebehaviourofCFSTjointssubjectedtostaticloading.Thepredictedresultsagreedwellwiththeexperimentaldata.(2)TheoreticalanalysiswascarriedoutusingtheFEmodelling.ThestrengthofCFSTjointsweremuchhigherthanthatofCHSjoints,andthefailuremodesofthemweredifferent,which220showsthatadoptingaconcrete-filledchordmemberisthemosteffectivewaytoimprovethestrengthofCHSjoints.(3)Withintherangeofthisstudy,thefailuremodesoftheKandKKCFSTjointswiththesamegeometrywerethesame,andtwotypesoffailuremodeswereobtained,includingyieldfailureofthecompressionbrace,andpunchingshearofthechord.o225(4)Forthe60CFSTjoints,themulti-planarcarry-overeffectshadthemaximumeffect,thestrengthofmulti-planarjointsdecreasedcomparedwiththeplanarjoints,whilethestiffnessofothemdidnotvarysubstantially.Forthe90CFSTjoints,boththestrengthandstiffnessofmulti-planarjointsdidnotvarysubstantiallywiththeplanarjoints.Acknowledgements230TheresearchworkdescribedinthispaperwassupportedbyNationalNaturalScienceFoundationofChina(No.51408308),SpecializedResearchFundfortheDoctoralProgramofHigherEducation(20133218120009),OpenResearchFundProgramofStatekeyLaboratoryofHydroscienceandEngineering(No.sklhse-2016-C-04),NUAAFundamentalResearchFund(No.NS2014001).235References[1]ChenJ,ZhangDW,JinWL.Concrete-FilledSteelandSteelTubularT-JointsunderCyclicin-PlaneBending[J].AdvancesinStructuralEngineering,2015,18(12):2207-2216.[2]UyB.Applications,BehaviourandDesignofCompositeSteel-ConcreteStructures[J].AdvancesinStructuralEngineering,2012,15(9):1559-1572.240[3]SakaiY,HosakaT,IsoeA,etal.ExperimentsonconcretefilledandreinforcedtubularK-jointsoftrussgirder[J].JournalofConstructionalSteelResearch,2004,60(3-5):683-699.[4]XuF,ChenJ,JinWL.ExperimentalinvestigationofSCFdistributionforthin-walledconcrete-filledCHSjointsunderaxialtensionloading[J].Thin-WalledStructures,2015,93:149-157.-11- 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中国科技论文在线http://www.paper.edu.cn模拟对钢管混凝土空间相贯节点的力学性能进行了研究。首先通过考虑材料非线性、几何非线性、管与混凝土之间的接触非线性，建立了钢管混凝土KK型相贯节点的精确有限元模型。通过与平面节点的比较，得到了空间节点的空间效应。有限元研究结果表明：空间效应对支管的横向夹角为60度的钢管混凝土空间相贯节点的影响最大，空间节点的强度与平面节点310相比有所降低，刚度相差不大；但是对于支管的横向夹角为90度的空间节点，其强度和刚度和平面节点的相差不大。该研究可为钢管混凝土空间相贯节点的设计提供科学依据，有效地促进钢管混凝土结构的应用。关键词：钢-混凝土组合结构；钢管相贯节点；空间节点；破坏模式；精确化有限元分析中图分类号：TU398.9315-13-'